Global Declaration SQL

Design


using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient; // 📌 SQL Server Database Connectivity

namespace SqlConect
{
    public partial class Form1 : Form
    {
        SqlConnection con = new SqlConnection();
        SqlCommand cmd = new SqlCommand();

        public Form1()
        {
            InitializeComponent();

            cmd.Connection = con;       
            con.ConnectionString = @"Data Source=DESKTOP-73VBH0K\SQLEXPRESS;Initial Catalog=FirstSQL;Integrated Security=True";
            con.Open();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // 📌 Load data into DataGridView
            this.detailsTableAdapter.Fill(this.firstSQLDataSet.Details);
        }

        private void btnInsert_Click(object sender, EventArgs e)
        {
            cmd.CommandText = "Insert Into [Table_Name] Values (" + textBox1.Text + ",'" + textBox2.Text + "','" + textBox3.Text + "'," + textBox4.Text + ")";
            cmd.ExecuteNonQuery();
            MessageBox.Show("✅ Record Inserted Successfully!");
        }

        private void btnUpdate_Click(object sender, EventArgs e)
        {
            cmd.CommandText = "Update [Table_Name] Set Student_Course = '" + textBox3.Text + "' Where Student_ID =" + textBox1.Text+ " ";
            cmd.ExecuteNonQuery();
            MessageBox.Show("📝 Record Updated Successfully!");
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            cmd.CommandText = "Delete From [Table_Name] Where Student_ID =" + textBox1.Text+ " ";
            cmd.ExecuteNonQuery();
            MessageBox.Show("🗑️ Record Deleted!");
        }

        private void btnSearch_Click(object sender, EventArgs e)
        {
            cmd.CommandText = "Select * From [Table_Name] Where Student_ID =" + textBox1.Text+ " ";
            SqlDataReader dr = cmd.ExecuteReader();

            if (dr.Read())
            {
                textBox1.Text = dr[0].ToString();
                textBox2.Text = dr[1].ToString();
                textBox3.Text = dr[2].ToString();
                textBox4.Text = dr[3].ToString();
            }
            MessageBox.Show("🔍 Record Found!");
        }

        private void txtSearch_TextChanged(object sender, EventArgs e)
        {
            cmd.CommandText = "Select * From [Table_Name] Where Student_Name Like '%" + textBox5.Text + "%'";
            SqlDataReader dr = cmd.ExecuteReader();

            DataTable dt = new DataTable();
            dt.Load(dr);

            dataGridView1.DataSource = dt;
            dataGridView1.Refresh();
        }
    }
}

Output